'use strict';

function even_to_letter(collection) {

  //在这里写入代码
  var str=['0','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
  'aa','ab','ac','ad','ae','af','ag', 'ah', 'ai', 'aj', 'ak', 'al', 'am', 'an', 'ao', 'ap',
  'aq', 'ar', 'as', 'at', 'au', 'av', 'aw', 'ax', 'ay',
  'az', 'ba'
  ];
  var a = [];
  var b = []
  for(let i = 0;i < collection.length;i++){
    if(collection[i]%2==0){
      a = collection[i]
    }
  }
  for(let i =0; i< a.length;i++){
    b[i] = str [a[i]]
  }
  return a;

}

module.exports = even_to_letter;
